Analysis of MAC Strategies for Underwater Acoustic Networks

En esta tesis presentamos los protocolos MAC diseñados para redes acústicas subacuáticas, clasificándolos en amplias categorías, proporcionando técnicas de medición de rendimiento y análisis comparativo para seleccionar el mejor algoritmo MAC para aplicaciones específicas. Floor Acquisition Multiple Access (FAMA) es un protocolo MAC que se propuso para redes acústicas submarinas como medio para resolver los problemas de terminales ocultos y expuestos. Una versión modificada, Slotted FAMA, tenía como objetivo proporcionar ahorros de energía mediante el uso de ranuras de tiempo, eliminando así la necesidad de paquetes de control excesivamente largos en FAMA. Sin embargo, se ha observado que, debido al alto retraso de propagación en estas redes, el coste de perder un ACK es muy alto y tiene un impacto significativo en el rendimiento. Los mecanismos MultiACK y EarlyACK han sido analizados para el protocolo MACA, para mejorar su eficiencia. El mecanismo MultiACK aumenta la probabilidad de recibir al menos un paquete ACK al responder con un tren de paquetes ACK, mientras que el mecanismo EarlyACK evita la repetición de todo el ciclo de contención y transmisión de datos RTS / CTS enviando un ACK temprano. En esta investigación se presenta un análisis matemático de las dos variantes, los mecanismos MultiACK y EarlyACK, en Slotted FAMA. La investigación incluye las expresiones analíticas modificadas así como los resultados numéricos. Las simulaciones se llevaron a cabo utilizando ns-3. Los resultados han sido probados y validados utilizando Excel y MATLAB. La evaluación del rendimiento de S-FAMA con dos variantes mostró un factor de mejora del 65,05% en la probabilidad de recibir un ACK correctamente utilizando el mecanismo MultiACK y del 60,58% en la prevención de la repetición del ciclo completo, con EarlyACK. El impacto de este factor de mejora en el retardo, el tamaño del paquete de datos y el rendimiento también se analiza. La energía de transmisión desperdiciada y consumida en los mecanismos MultiACK y EarlyACK se analizan y comparan con S-FAMA. El rendimiento se ha evaluado, alcanzando una mejora en ambos casos, en comparación con S-FAMA. Estos mecanismos tendrán una utilidad práctica en caso de pérdida de ACK, al ahorrar energía y tiempo en períodos críticos. Fecha de lectura de Tesis Doctoral: 28 septiembre 2018.Esta tesis presenta una investigación sobre los protocolos MAC utilizados en la comunicación subacuática para explorar el mundo submarino. Los protocolos MAC ayudan en el acceso al medio compartido y la recopilación de datos de los océanos, para monitorizar el clima y la contaminación, la prevención de catástrofes, la navegación asistida, la vigilancia estratégica y la exploración de los recursos minerales. Esta investigación beneficiará a sectores como las industrias militares, de petróleo y gas, pesquerías, compañías de instrumentación subacuática, organismos de investigación, etc. El protocolo MAC afecta la vida útil de las redes inalámbricas de sensores. La eficiencia energética de las redes acústicas submarinas se ve gravemente afectada por las propiedades típicas de la propagación de las ondas acústicas. Los largos retrasos de propagación y las colisiones de paquetes de datos dificultan la transmisión de los paquetes de datos, que contienen información útil para que los usuarios realicen tareas de supervisión colectivas. El objetivo de este estudio es proponer nuevos mecanismos para protocolos MAC diseñados para funcionar en redes acústicas submarinas, con el propósito de mejorar su rendimiento. Para alcanzar ese objetivo es necesario realizar un análisis comparativo de los protocolos existentes. Lo que además sienta un procedimiento metodológicamente correcto para realizar esa comparación. Como la comunicación subacuática depende de ondas acústicas, en el diseño de los protocolos de MAC submarinos surgen varios desafíos como latencia prolongada, ancho de banda limitado, largas demoras en la propagación, grandes tasas de error de bit, pérdidas momentáneas en las conexiones, severo efecto multicamino y desvanecimientos. Los protocolos MAC terrestres, si se implementan directamente, funcionarán de manera ineficiente

Comparative Analysis of Routing and Wavelength Assignment Algorithms used

Abstract: This study aims at highlighting the Routing and Wavelength Assignment (RWA) problems in WDM Optical networks and describes the Routing Algorithms and their performance comparison. Since routing decisions play an important role in evaluating the blocking performance of a network it is critical to choose a wavelength assignment scheme that should take into account its compatibility with the chosen routing protocol in addition to its blocking performance. This study presents problems in Wavelength Assignment, describes various Routing schemes and different approaches to solve both the static and the dynamic RWA problems. RWA algorithms' role is to assign a light-path (a route and a wavelength) to incoming calls in a network. RWA algorithms block calls if a continuous wavelength from source to destination cannot be found (wavelength blocking), thus degrading the performance of All Optical Networks, by call blocking. The failure of RWA algorithm to find an available wavelength on all links from source to destination causes congestion resulting in packet loss. This study examines the RWA algorithms and their problems in WDM Optical networks. The various measures taken to improve the blocking performance of WDM optical networks are also studied. We compared the performance of two wavelength assignment schemes, the Random wavelength assignment and the First-Fit wavelength assignment scheme via simulation. It was observed that the Random wavelength assignment algorithm performs well under low load, while for high load First Fit algorithm performs better

Research in Pakistan: Structure, Funding and Results

In Pakistan Higher Education Commission (HEC) is consideredas the centralized body that governs and sets policies forresearch and development for all educational institutions ofhigher learning. Availability of research material is one of themain hurdles in the production and creativity of manyresearchers in all disciplines at university level. Dearth of suchfacilities demotivates the young researchers, and they startlooking for opportunities in the urban countries. HEC has madethe first move by starting National Research Program forUniversities (NRPU) by promoting the Research &development to meet the current challenges. The aim of thisresearch is to provide the research status in Pakistan, itsstructure, funding and results. The support of the governmentto researchers plays a vital role. Some bottlenecks that havebeen identified are: centralized system, processing delays inapproval of funds and projects and slow execution of policiesThe delays in the approval and release of funds affect the systemand interest of researchers. Poor check on policy implementationresults in economic loss to the country. HEC is trying toencourage research culture in Pakistan; The HEC supportsresearchers based on their ability and impact factor with amaximum funding of 20 Million. It provides grants for researchprojects in the fields of Engineering, Science & Technology aswell as humanities and social sciences. The objective is toencourage research in all fields and branches of learnin

Doppler ultrasound scoring to predict chemotherapeutic response in advanced breast cancer

<p>Abstract</p> <p>Background</p> <p>Doppler ultrasonography (US) is increasingly being utilized as an imaging modality in breast cancer. It is used to study the vascular characteristics of the tumor. Neoadjuvant chemotherapy is the standard modality of treatment in locally advanced breast cancer. Histological examination remains the gold standard to assess the chemotherapy response. However, based on the color Doppler findings, a new scoring system that could predict histological response following chemotherapy is proposed.</p> <p>Methods</p> <p>Fifty cases of locally advanced infiltrating duct carcinoma of the breast were studied. The mean age of the patients was 44.5 years. All patients underwent clinical, Doppler and histopathological assessment followed by three cycles of CAF (Cyclophosphamide, Adriamycin and 5-Fluorouracil) chemotherapy, repeat clinical and Doppler examination and surgery. The resected specimens were examined histopathologically and histological response was correlated with Doppler findings. The Doppler characteristics of the tumor were graded as 1–4 for <25%, 25–50%, >50% and complete disappearance of flow signals respectively. A cumulative score was calculated and compared with histopathological response. Results were analyzed using Chi square test, sensitivity, specificity, positive and negative predictive values.</p> <p>Results</p> <p>The maximum Doppler score according to the proposed scoring system was twelve and minimum three. Higher scores corresponded with a more favorable histopathological response. Twenty four patients had complete response to chemotherapy. Sixteen of these 24 patients (66.7%) had a cumulative Doppler score more than nine. The sensitivity of cumulative score >5 was 91.7% and specificity was 38.5%. The area under the ROC curve of the cumulative score >9 was 0.72.</p> <p>Conclusion</p> <p>Doppler scoring can be accurately used to objectively predict the response to chemotherapy in patients with locally advanced breast cancer and it correlates well with histopathological response.</p

High-Grade B-cell Lymphoma, Not Otherwise Specified: A Multi-Institutional Retrospective Study

In this multi-institutional retrospective study, we examined the characteristics and outcomes of 160 patients with high-grade B-cell lymphoma, not otherwise specified (HGBL-NOS)-a rare category defined by high-grade morphologic features and lack of MYC rearrangements with BCL2 and/or BCL6 rearrangements ( double hit ). Our results show that HGBL-NOS tumors are heterogeneous: 83% of patients had a germinal center B-cell immunophenotype, 37% a dual-expressor immunophenotype (MYC and BCL2 expression), 28% MYC rearrangement, 13% BCL2 rearrangement, and 11% BCL6 rearrangement. Most patients presented with stage IV disease, a high serum lactate dehydrogenase, and other high-risk clinical factors. Most frequent first-line regimens included dose-adjusted cyclophosphamide, doxorubicin, vincristine, and etoposide, with rituximab and prednisone (DA-EPOCH-R; 43%); rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP; 33%); or other intensive chemotherapy programs. We found no significant differences in the rates of complete response (CR), progression-free survival (PFS), or overall survival (OS) between these chemotherapy regimens. CR was attained by 69% of patients. PFS at 2 years was 55.2% and OS was 68.1%. In a multivariable model, the main prognostic factors for PFS and OS were poor performance status, lactate dehydrogenase \u3e3 × upper limit of normal, and a dual-expressor immunophenotype. Age \u3e60 years or presence of MYC rearrangement were not prognostic, but patients with TP53 alterations had a dismal PFS. Presence of MYC rearrangement was not predictive of better PFS in patients treated with DA-EPOCH-R vs R-CHOP. Improvements in the diagnostic criteria and therapeutic approaches beyond dose-intense chemotherapy are needed to overcome the unfavorable prognosis of patients with HGBL-NOS

Technologies Trend in the Integration of 5G Networks and IoT in Smart Cities: A Survey

— This paper presents a survey of 5G and suitable concerns in the planning and development of communication model infrastructure for the deployment of Smart Cities, also called Intelligent Cities or Digital Cities. The paper first provides an overview of 5G technology, its evolution, and how it revolutionised worldwide communication. The drivers of 5G, such as enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine-type communication (mMTC), will enable 5G to deliver higher speeds compared to the previous 4G and 3G generations and enable service providers to provide massive bandwidth catering to data-intensive applications such as Smart Cities. Besides human-computer interaction (HCI), smart cities include machine type communication (MTC), in which massive communication takes place between devices and the information infrastructure through gateways. A 5G network can successfully integrate the diversified service requirements and demands of smart city applications. Smart cities require massive IoT communication built into 5G. Multiple technologies are deployed in smart cities to enhance the standard of living for people. Citizens are provided with better health services, improved transportation, efficient energy, quality education, and safety and security to public. In this survey paper we present the contribution of 5G in the deployment of smart city applications and its pillars that play a very important role in the construction of smart cities. Better healthcare systems have been developed that integrate new communication technologies and conventional health care procedures. One of the vital segments of a smart city is its transportation system, which affects the environs and health of people. The energy efficiency of smart cities can be greatly improved by 5G by using smart appliances. Smart metres deliver real-time data about the energy consumed. Users can save energy and money. Similarly, it can assist the water board team by giving real-time statistics regarding water consumption to the consumers. Almost all the smart city infrastructure mentioned above has different requirements for delay, movement, dependability, and resilience of the network. Incorporating diverse applications into a communication network is a difficult chore. 5G has been designed for forward compatibility to support future amenities not known today. The paper outlines diverse requirements for smart cities based on application and technology requirements. Lastly, the supporting technologies are highlighted for the forthcoming integration of smart cities and communication infrastructure

Capability Maturity Model Integration Within The Admission Processes Of Academic Institutions In Pakistan

One of the important foundations of any society is the education provided by the universities to the students. ­There are various levels of educational institutions from IV league to ordinary colleges. ­The gradation of these institutions is very informal and need proper mechanism to assess them and improve their standards. ­There are national bodies’ setup in our country for the purpose of assessment of quality assurance such as HEC and PEC but many of the institutions; they do not go for external audit of the process implemented within the institution. ­is research aims to assess the processes in renowned institutions, measure their level of maturity for improvement where feasible. In this research paper three models have been presented; Documented Model, Actual Model and Proposed Model. ­e “Admission Processes” of two renowned institutions have been chosen for the purpose of assessment. Capability Maturity Model Integration (CMMI) has been used to measure the maturity level of the Actual Model. Weaknesses in Actual Models were identified and solutions have been proposed to upgrade the institutions’ Admission Process Level. The main focus of this research is on the existing “Admission Processes” within the institutions and how to improve them using CMMI. Our analysis shows that proposed model with CMMI level-3 removes the major weaknesses and upgrade the institutions’ Admission Process Level. Analysis shows that after mapping Admission Process of Educational Institution-1 and Educational Institution-2 onto the process areas of Capability Maturity Model Integration it has been found that Maturity Level of Educational Institute-1 is 32.04% and Maturity Level of Educational Institution-2 is 39.54%. Maturity Levels of both Institutions are near to Maturity Level 2. Model has been proposed with Maturity Level 3 for both institutions which is graded as good and rated at 60%. After the practical implementation of proposed model, the Maturity Level can be further improved to 4 and 5, which are graded as excellent and ideal respectively

Telecommunication Trends in Pakistan

Pakistan's telecommunication market is one of the world's fastest growing industry. The Telecom sector is growing at a pace of 170% yearly. Pakistan has a population of more than 160 million and the number of mobile phone subscribers are 78.73 million as of January 2008. According to Pakistan Telecommunication Authority (PTA), 2.7 million subscribers are added monthly (ntcpk n.d.), The PTA expects the number to cross 100 million users by 2010 (Johnson n.d.).This paper presents Telecommunication trends in Pakistan with a focus on: one, the economic development, and development trends of Pakistan telecommunication industry, two, Communication Infrastructure, three, Mobile phone adoption, four market survey and analysis, and five the teledensity comparison of Pakistan with other South Asian countries